[PATCH v2 1/4] git-gui: provide question helper for retry fallback on Windows

["Heiko Voigt via GitGitGadget" <gitgitgadget@gmail.com>]

From: Heiko Voigt <hvoigt@hvoigt.net>

Make use of the new environment variable GIT_ASK_YESNO to support the
recently implemented fallback in case unlink, rename or rmdir fail for
files in use on Windows. The added dialog will present a yes/no question
to the the user which will currently be used by the windows compat layer
to let the user retry a failed file operation.

Signed-off-by: Heiko Voigt <hvoigt@hvoigt.net>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 Makefile          |  2 ++
 git-gui--askyesno | 42 ++++++++++++++++++++++++++++++++++++++++++
 git-gui.sh        |  3 +++
 3 files changed, 47 insertions(+)
 create mode 100755 git-gui--askyesno

diff --git a/Makefile b/Makefile
index 2cd160b05755..6385db443929 100644
--- a/Makefile
+++ b/Makefile
@@ -185,6 +185,7 @@ install: all
 	$(QUIET)$(INSTALL_D0)'$(DESTDIR_SQ)$(gitexecdir_SQ)' $(INSTALL_D1)
 	$(QUIET)$(INSTALL_X0)git-gui $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(QUIET)$(INSTALL_X0)git-gui--askpass $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
+	$(QUIET)$(INSTALL_X0)git-gui--askyesno $(INSTALL_X1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(QUIET)$(foreach p,$(GITGUI_BUILT_INS), $(INSTALL_L0)'$(DESTDIR_SQ)$(gitexecdir_SQ)/$p' $(INSTALL_L1)'$(DESTDIR_SQ)$(gitexecdir_SQ)/git-gui' $(INSTALL_L2)'$(DESTDIR_SQ)$(gitexecdir_SQ)/$p' $(INSTALL_L3) &&) true
 ifdef GITGUI_WINDOWS_WRAPPER
 	$(QUIET)$(INSTALL_R0)git-gui.tcl $(INSTALL_R1) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
@@ -199,6 +200,7 @@ uninstall:
 	$(QUIET)$(CLEAN_DST) '$(DESTDIR_SQ)$(gitexecdir_SQ)'
 	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui $(REMOVE_F1)
 	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui--askpass $(REMOVE_F1)
+	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui--askyesno $(REMOVE_F1)
 	$(QUIET)$(foreach p,$(GITGUI_BUILT_INS), $(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/$p $(REMOVE_F1) &&) true
 ifdef GITGUI_WINDOWS_WRAPPER
 	$(QUIET)$(REMOVE_F0)'$(DESTDIR_SQ)$(gitexecdir_SQ)'/git-gui.tcl $(REMOVE_F1)
diff --git a/git-gui--askyesno b/git-gui--askyesno
new file mode 100755
index 000000000000..f7312c70c2ca
--- /dev/null
+++ b/git-gui--askyesno
@@ -0,0 +1,42 @@
+#!/bin/sh
+# Tcl ignores the next line -*- tcl -*- \
+exec wish "$0" -- "$@"
+
+# This is an implementation of a simple yes no dialog
+# which is injected into the git commandline by git gui
+# in case a yesno question needs to be answered.
+
+set NS {}
+set use_ttk [package vsatisfies [package provide Tk] 8.5]
+if {$use_ttk} {
+	set NS ttk
+}
+
+if {$argc < 1} {
+	puts stderr "Usage: $argv0 <question>"
+	exit 1
+} else {
+	set prompt [join $argv " "]
+}
+
+${NS}::frame .t
+${NS}::label .t.m -text $prompt -justify center -width 40
+.t.m configure -wraplength 400
+pack .t.m -side top -fill x -padx 20 -pady 20 -expand 1
+pack .t -side top -fill x -ipadx 20 -ipady 20 -expand 1
+
+${NS}::frame .b
+${NS}::frame .b.left -width 200
+${NS}::button .b.yes -text Yes -command {exit 0}
+${NS}::button .b.no  -text No  -command {exit 1}
+
+pack .b.left -side left -expand 1 -fill x
+pack .b.yes -side left -expand 1
+pack .b.no -side right -expand 1 -ipadx 5
+pack .b -side bottom -fill x -ipadx 20 -ipady 15
+
+bind . <Key-Return> {exit 0}
+bind . <Key-Escape> {exit 1}
+
+wm title . "Question?"
+tk::PlaceWindow .
diff --git a/git-gui.sh b/git-gui.sh
index a931d7f7c990..1a4b73a3373a 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -1130,6 +1130,9 @@ set argv0dir [file dirname [file normalize $::argv0]]
 if {![info exists env(SSH_ASKPASS)]} {
 	set env(SSH_ASKPASS) [file join $argv0dir git-gui--askpass]
 }
+if {![info exists env(GIT_ASK_YESNO)]} {
+	set env(GIT_ASK_YESNO) [file join $argv0dir git-gui--askyesno]
+}
 unset argv0dir
 
 ######################################################################
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